Figure 3. Exclusion of potential interference between different resistance genes using strains showing either Zeocin, nourseothricin or blasticidin-S resistance.

(A) Nine blasticidin-S-resistant P. tricornutum colonies were spread on plates containing Zeocin or nourseothricin and on a control plate containing blasticidin-S. (B) Nine Zeocin-resistant colonies were spread on blasticidin-S plates and on control plates with Zeocin. (C) Nine nourseothricin-resistant colonies were spread on plates with blasticidin-S and on control plates with nourseothricin. The cells were able to survive only on the appropriate antibiotics. (+) = growth of the cells; (−) = no growth.